real—we watch them grow from eggs to lame fish or whatever to powerful

Everybody loves Pokémon. Over 15 million people have downloaded Pokémon Go, and many of them are likely rekindling their childhood love for the addicting Japanese cartoons. Nearly everyone, it seems, is catching and training and breeding and evolving Pokémon. The creatures can feel embarrassingly, achingly, real—we watch them grow from eggs to lame fish or whatever to powerful, gym-conquering monsters with actual, genuine compassion.

But how do Pokémon fuck? That’s all I’m asking.

You can’t figure out the answer to this question by talking to Nintendo. (I tried, but didn’t get a response.) Google is also no help, because you just end up learning about a 2015 Pokémon porn parody called Strokemon (Tagline: "Gotta bang ’em all!"), which features a scene in which Ash and Misty have a threesome with Pikachu. I contacted Woodrocket, the production company behind Strokemon, to ask if they’d done any research about how Pokémon fuck. Via text, a Woodrocket rep told me, "Lol no we did not."

OK, so what do we know from the games? All Pokémon lay eggs. Two Pokémon can create an egg together if they’re of opposite genders and are members of the same "egg group" (loose categorizations of similar-ish Pokémon with names like "Fairy," "Mineral," "Bug," and "Field"). In the original games, you leave the two together at a Pokémon daycare and then come back to find an egg. In Pokémon Go, you just come across eggs with no explanation. Clearly, the game’s designers did not want you to think how two Pikachus come together to make a third. And yet…

"I suspect there’s a lot of different ways that different Pokémon go about [having sex]," said T. Ryan Gregory, an evolutionary biologist and zoologist who runs the Gregory Lab of Genomic Diversity at the University of Guelph in Ontario. He was nice enough to return my call, and even agreed to use the scant pre-existing info on Pokésex as a jumping-off point for "actually coming up with some hypotheses of what you’re most likely to find."

The fact that all Pokémon lay eggs is logical from an evolutionary perspective, Gregory told me. If Pokémon are going around all day trying to find other Pokémon to do battle with, he said, "a prolonged period of gestation would be very difficult. It would make a lot more sense to have external eggs." But the fact that Pokémon all lay eggs also offer us a clue that there’s a certain commonality between them that would allow wildly different-looking types of Pokémon breeds to produce offspring together. Said Gregory, "They all go through a very similar early stage—the egg stage—and then their differences arise later in their development."

With all this in mind, Gregory said that if he had to guess, most Pokémon probably have sex in one of two broad ways. Many Pokémon are bilaterally symmetrical, which Gregory defines as "two matched sides with a head at the front and a butt at the back," as well as a set of genitalia between their legs. Most bilaterally symmetrical animals engage in internal fertilization—a.k.a. penis-in-vagina sex. So essentially, any Pokémon that looks like it has legs, arms, and a head probably also has genitals, and probably uses those genitals in ways we’re familiar with. In other words, maybe Strokemon is more accurate than its creators intended.

It gets trickier when you’re dealing with Pokémon such as Cloyster (the one that looks like an oyster) or Bellsprout (the one that looks like a flower, kinda), which lack that same bilateral symmetry. Those breeds probably have sex via external fertilization, where a female Pokémon would lay an egg that would then be fertilized by a male, either by him shooting his sperm into the egg or through broadcast spawning, which basically involves males "shooting massive quantities of sperm everywhere, which females then take in."

Josh Dunlop, a concept artist who creates realistic renditions of Pokémon, told me he thought that legless, amorphous egg-type Pokémon such as the ghost-like Gastly and Koffing probably engaged in a similar, albeit more mythical form of external fertilization in which the male Pokémon would deposit his sperm by gliding through the female’s eggs. And who is going to argue with him?

It turns out that Pokémon egg groups—the interconnected networks of physically similar Pokémon who can mate with each other within the game—might also explain how Pokémon with such vastly different sex styles might be able to exist within the same basic taxonomy. Egg groups, Gregory said, are actually fairly similar to a naturally occurring phenomenon called ring species, which he describes as "the series of connections that unify two things that appear to be quite different." Each egg group represents a "ring" in the network, he said, and if you were to pick two Pokémon at random—Squirtle and Rapidash, say—they might not be able to breed together, but you could link them through a series of Pokémon who could breed together. In this instance, Squirtle is listed under the Monster and Water 1 egg groups, which means that Squirtle could breed with any other member of those egg groups. Get a Squirtle and a Rhyhorn (a member of the Monster and Field egg groups) together, and they can produce an egg. And since Rapidash is also a member of the Field egg group, it too can breed with Rhyhorn.

But I digress. I imagine you want to know which Pokémon have dicks. Externally fertilizing Pokémon would generally not, but some Pokémon who fertilized internally, Gregory said, "might have really crazy ones. Duck penises are curved and really long, and cat penises are spiky. If you look at certain insects, the females have special shapes for scooping out sperm from the males, while other insects’ penises break off." If you’re keeping score at home, that means Psyduck has a spiral-y dick, Mewtwo has a spiky one, and Pinsir might have whatever the hell this is.